In general, a well is a structure that provides access, or communication, between a surface region and a subterranean formation. Illustrative, non-exclusive examples of access may include fluid access or fluid communication (or similarly hydraulic access or hydraulic communication), mechanical access or mechanical communication, data access or data communication, electrical access or electrical communication, and/or any suitable combination of these. Illustrative, non-exclusive examples of fluid access or fluid communication may include providing a stimulant fluid from the surface region to the subterranean formation and/or producing a reservoir fluid from the subterranean formation to the surface region. Illustrative, non-exclusive examples of mechanical access or mechanical communication may include supplying a drill bit or other mechanical equipment from the surface region to the subterranean formation and/or performing a drilling operation with the drill bit in the subterranean formation. Illustrative, non-exclusive examples of data access or data communication may include supplying well-monitoring equipment, such as temperature, pressure, chemical composition, and/or flow rate monitoring equipment from the surface region to the subterranean formation and/or monitoring a status of the well with the monitoring equipment. Illustrative, non-exclusive examples of electrical access or electrical communication may include communicating with the well-monitoring equipment discussed above, as well as supplying electrical current to a subsurface region and/or to one or more devices contained within the wellbore to, for instance, provide heat to at least a portion of the subsurface region.
Historically, access between the surface region and the subterranean formation has been accomplished using single point-of-entry, or mono-entry, wells. This type of well includes a single point-of-entry to drill the well, complete the well structure, produce fluids from the subterranean formation, provide fluids to the subterranean formation, service the well, and/or monitor the status of the well. While these mono-entry wells may include multiple fluid flow pathways or conduits below the surface region, all of these fluid flow pathways communicate with the surface region via the single point-of-entry.
Under certain circumstances, relying on a single point-of-entry for access between the surface region and the subterranean formation may be problematic, or at least inefficient. As an illustrative, non-exclusive example, a well may be damaged or subjected to conditions in which it experiences an uncontrolled flow of fluid from the well, which also may be called a blowout. Under these circumstances, the traditional, single point-of-entry well may not provide the level of access needed to stop the blowout, and other techniques may need to be utilized. This may include the drilling of a relief well that intersects the original well at a point in the subsurface region, which provides a second point-of-entry into the well, and which may provide the level of access needed to control the blowout and/or kill the well. As another illustrative, non-exclusive example, single point-of-entry wells may limit the rate at which the well may be drilled or completed, and/or may limit enhanced recovery and/or abandonment operations due to the limitations of having only the single point-of-entry, especially with respect to the terminal depth(s) of the well's casing.
Thus, there exists a need for systems and methods to provide improved well access between the surface region and the subterranean formation.